''Planck'' was a
space observatory
A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first operational telescopes were the American Orbiting Astronomical Observatory, OAO-2 launche ...
operated by the
European Space Agency (ESA) from 2009 to 2013, which mapped the
anisotropies
Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...
of the
cosmic microwave background
In Big Bang cosmology the cosmic microwave background (CMB, CMBR) is electromagnetic radiation that is a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all spac ...
(CMB) at microwave and infrared frequencies, with high sensitivity and small
angular resolution. The mission substantially improved upon observations made by the
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
Wilkinson Microwave Anisotropy Probe (WMAP). ''Planck'' provided a major source of information relevant to several cosmological and astrophysical issues, such as testing theories of the early Universe and the origin of cosmic structure. Since the end of its mission, ''Planck'' has defined the most precise measurements of several key cosmological parameters, including the average density of ordinary
matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic part ...
and
dark matter
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not a ...
in the Universe and the
age of the universe
In physical cosmology, the age of the universe is the time elapsed since the Big Bang. Astronomers have derived two different measurements of the age of the universe:
a measurement based on direct observations of an early state of the universe, ...
.
The project was started around 1996 and was initially called COBRAS/SAMBA: the Cosmic Background Radiation Anisotropy Satellite/Satellite for Measurement of Background Anisotropies. It was later renamed in honour of the German physicist
Max Planck
Max Karl Ernst Ludwig Planck (, ; 23 April 1858 – 4 October 1947) was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918.
Planck made many substantial contributions to theoretical p ...
(1858–1947), who became the originator of
quantum theory
Quantum theory may refer to:
Science
*Quantum mechanics, a major field of physics
*Old quantum theory, predating modern quantum mechanics
* Quantum field theory, an area of quantum mechanics that includes:
** Quantum electrodynamics
** Quantum ...
by deriving the formula for
black-body radiation.
Built at the
Cannes Mandelieu Space Center
The Cannes Mandelieu Space Center is an industrial plant dedicated to spacecraft manufacturing, located in both the towns of Cannes and Mandelieu in France. After a long history in aircraft manufacturing, starting in 1929, the center became incre ...
by
Thales Alenia Space
Thales Alenia Space () is a Franco-Italian aerospace manufacturer. A joint venture between the French technology corporation Thales Group (67%) and Italian defense conglomerate Leonardo (33%), the company is the largest satellite manufactur ...
, and created as a medium-sized mission for ESA's
Horizon 2000
The Science Programme of the European Space Agency is a long-term programme of space science and space exploration missions. Managed by the agency's Directorate of Science, The programme funds the development, launch, and operation of missions ...
long-term scientific programme, ''Planck'' was launched in May 2009.
It reached the Earth/Sun by July 2009, and by February 2010 it had successfully started a second all-sky survey. On 21 March 2013, the mission's first all-sky map of the cosmic microwave background was released with an additional expanded release including
polarization data in February 2015. The final papers by the ''Planck'' team were released in July 2018.
At the end of its mission ''Planck'' was put into a
heliocentric graveyard orbit
A graveyard orbit, also called a junk orbit or disposal orbit, is an orbit that lies away from common operational orbits. One significant graveyard orbit is a supersynchronous orbit well beyond geosynchronous orbit. Some satellites are moved into ...
and
passivated to prevent it from endangering any future missions. The final deactivation command was sent to ''Planck'' in October 2013.
Objectives
The mission had a wide variety of scientific aims, including:
* high resolution detections of both the total intensity and polarization of primordial
CMB anisotropies,
* creation of a catalogue of
galaxy clusters
A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-l ...
through the
Sunyaev–Zel'dovich effect,
* observations of the
gravitational lens
A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known ...
ing of the CMB, as well as the integrated
Sachs–Wolfe effect,
* observations of bright extragalactic radio (
active galactic nuclei
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ...
) and infrared (dusty galaxy) sources,
* observations of the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
, including the
interstellar medium, distributed
synchrotron emission and measurements of the Galactic
magnetic field, and
* studies of the
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
, including
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s,
asteroids,
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s and the
zodiacal light
The zodiacal light (also called false dawn when seen before sunrise) is a faint glow of diffuse sunlight scattered by interplanetary dust. Brighter around the Sun, it appears in a particularly dark night sky to extend from the Sun's direction ...
.
''Planck'' had a higher resolution and sensitivity than WMAP, allowing it to probe the power spectrum of the CMB to much smaller scales (×3). It also observed in nine
frequency
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
bands rather than WMAP's five, with the goal of improving the astrophysical foreground models.
It is expected that most ''Planck'' measurements have been limited by how well foregrounds can be subtracted, rather than by the detector performance or length of the mission, a particularly important factor for the
polarization measurements. The dominant foreground radiation depends on frequency, but could include synchrotron radiation from the Milky Way at low frequencies, and dust at high frequencies.
Instruments
The spacecraft carries two instruments: the Low Frequency Instrument (LFI) and the High Frequency Instrument (HFI).
Both instruments can detect both the total intensity and
polarization of photons, and together cover a frequency range of nearly 830 GHz (from 30 to 857 GHz). The cosmic microwave background spectrum peaks at a frequency of 160.2 GHz.
''Planck'' passive and active cooling systems allow its instruments to maintain a temperature of , or 0.1 °C above
absolute zero. From August 2009, ''Planck'' was the coldest known object in space, until its active coolant supply was exhausted in January 2012.
NASA played a role in the development of this mission and contributes to the analysis of scientific data. Its
Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States.
Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...
built components of the science instruments, including
bolometer
A bolometer is a device for measuring radiant heat by means of a material having a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley.
Principle of operation
A bolometer ...
s for the high-frequency instrument, a 20-kelvin
cryocooler
A refrigerator designed to reach cryogenic temperatures (below ) is often called a cryocooler. The term is most often used for smaller systems, typically table-top size, with input powers less than about 20 kW. Some can have input powers as l ...
for both the low- and high-frequency instruments, and amplifier technology for the low-frequency instrument.
Low Frequency Instrument
The LFI has three frequency bands, covering the range of 30–70 GHz, covering the microwave to infrared regions of the electromagnetic spectrum. The detectors use
high-electron-mobility transistor
A high-electron-mobility transistor (HEMT), also known as heterostructure FET (HFET) or modulation-doped FET (MODFET), is a field-effect transistor incorporating a junction between two materials with different band gaps (i.e. a heterojunction) ...
s.
High Frequency Instrument
The HFI was sensitive between 100 and 857 GHz, using 52
bolometric
A bolometer is a device for measuring radiant heat by means of a material having a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley.
Principle of operation
A bolometer ...
detectors, manufactured by JPL/Caltech, optically coupled to the telescope through cold optics, manufactured by Cardiff University's School of Physics and Astronomy, consisting of a triple horn configuration and optical filters, a similar concept to that used in the
Archeops balloon-borne experiment. These detection assemblies are divided into 6 frequency bands (centred at 100, 143, 217, 353, 545 and 857 GHz), each with a bandwidth of 33%. Of these six bands, only the lower four have the capability to measure the polarisation of incoming radiation; the two higher bands do not.
On 13 January 2012, it was reported that the on-board supply of
helium-3 used in ''Planck''
dilution refrigerator
A 3He/4He dilution refrigerator is a cryogenic device that provides continuous cooling to temperatures as low as 2 mK, with no moving parts in the low-temperature region. The cooling power is provided by the heat of mixing of the Hel ...
had been exhausted, and that the HFI would become unusable within a few days.
By this date, ''Planck'' had completed five full scans of the CMB, exceeding its target of two. The LFI (cooled by
helium-4
Helium-4 () is a stable isotope of the element helium. It is by far the more abundant of the two naturally occurring isotopes of helium, making up about 99.99986% of the helium on Earth. Its nucleus is identical to an alpha particle, and consis ...
) was expected to remain operational for another six to nine months.
Service module
A common
service module
A service module (also known as an equipment module or instrument compartment) is a component of a crewed space capsule containing a variety of support systems used for spacecraft operations. Usually located in the uninhabited area of the spacec ...
(SVM) was designed and built by Thales Alenia Space in its
Turin
Turin ( , Piedmontese: ; it, Torino ) is a city and an important business and cultural centre in Northern Italy. It is the capital city of Piedmont and of the Metropolitan City of Turin, and was the first Italian capital from 1861 to 1865. The ...
plant, for both the ''
Herschel Space Observatory'' and ''Planck'' missions, combined into one single program.
The overall cost is estimated to be for the ''Planck'' and for the ''Herschel'' mission. Both figures include their mission's spacecraft and payload, (shared) launch and mission expenses, and science operations.
Structurally, the ''Herschel'' and ''Planck'' SVMs are very similar. Both SVMs are octagonal in shape and each panel is dedicated to accommodate a designated set of warm units, while taking into account the dissipation requirements of the different warm units, of the instruments, as well as the spacecraft. On both spacecraft, a common design was used for the
avionics
Avionics (a blend of ''aviation'' and ''electronics'') are the electronic systems used on aircraft. Avionic systems include communications, navigation, the display and management of multiple systems, and the hundreds of systems that are fit ...
, attitude control and measurement (ACMS), command and data management (CDMS), power, and tracking, telemetry and command (TT&C) subsystems. All units on the SVM are redundant.
Power Subsystem
On each spacecraft, the power subsystem consists of a
solar array
A photovoltaic system, also PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and ...
, employing triple-junction
solar cell
A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. s, a
battery
Battery most often refers to:
* Electric battery, a device that provides electrical power
* Battery (crime), a crime involving unlawful physical contact
Battery may also refer to:
Energy source
*Automotive battery, a device to provide power t ...
and the power control unit (PCU). The PCU is designed to interface with the 30 sections of each solar array, to provide a regulated 28 volt bus, to distribute this power via protected outputs, and to handle the battery charging and discharging.
For ''Planck'', the circular solar array is fixed on the bottom of the satellite, always facing the Sun as the satellite rotates on its vertical axis.
Attitude and Orbit Control
This function is performed by the attitude control computer (ACC), which is the platform for the attitude control and measurement subsystem (ACMS). It was designed to fulfil the pointing and slewing requirements of the ''Herschel'' and ''Planck'' payloads.
The ''Planck'' satellite
rotates at one revolution per minute, with an aim of an absolute pointing error less than 37 arc-minutes. As ''Planck'' is also a survey platform, there is the additional requirement for pointing reproducibility error less than 2.5 arc-minutes over 20 days.
The main line-of-sight sensor in both ''Herschel'' and ''Planck'' is the
star tracker
A star tracker is an optical device that measures the positions of stars using photocells or a camera.
As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...
.
Launch and orbit
The satellite was successfully launched, along with the ''
Herschel Space Observatory'', at 13:12:02 UTC on 14 May 2009 aboard an
Ariane 5 ECA heavy launch vehicle from the
Guiana Space Centre
The Guiana Space Centre (french: links=no, Centre spatial guyanais; CSG), also called Europe's Spaceport, is a European spaceport to the northwest of Kourou in French Guiana, a region of France in South America. Kourou is located approximatel ...
. The launch placed the craft into a very elliptical orbit (
perigee
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two apsides in any ell ...
: ,
apogee
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion.
General description
There are two apsides in any ell ...
: more than ), bringing it near the Lagrangian point of the
Earth-Sun system, from the Earth.
The manoeuvre to inject ''Planck'' into its final orbit around was successfully completed on 3 July 2009, when it entered a
Lissajous orbit with a radius around the Lagrangian point.
The temperature of the High Frequency Instrument reached just a tenth of a degree above absolute zero (0.1
K) on 3 July 2009, placing both the Low Frequency and High Frequency Instruments within their cryogenic operational parameters, making ''Planck'' fully operational.
Decommissioning
In January 2012 the HFI exhausted its supply of liquid helium, causing the detector temperature to rise and rendering the HFI unusable. The LFI continued to be used until science operations ended on 3 October 2013. The spacecraft performed a manoeuvre on 9 October to move it away from Earth and its , placing it into a
heliocentric orbit, while payload deactivation occurred on 19 October. ''Planck'' was commanded on 21 October to exhaust its remaining fuel supply;
passivation activities were conducted later, including battery disconnection and the disabling of protection mechanisms.
The final deactivation command, which switched off the spacecraft's transmitter, was sent to ''Planck'' on 23 October 2013 at 12:10:27 UTC.
Results
''Planck'' started its First All-Sky Survey on 13 August 2009.
In September 2009, the
European Space Agency announced the preliminary results from the ''Planck First Light Survey'', which was performed to demonstrate the stability of the instruments and the ability to calibrate them over long periods. The results indicated that the data quality is excellent.
On 15 January 2010 the mission was extended by 12 months, with observation continuing until at least the end of 2011. After the successful conclusion of the First Survey, the spacecraft started its Second All Sky Survey on 14 February 2010, with more than 95% of the sky observed already and 100% sky coverage being expected by mid-June 2010.
Some planned pointing list data from 2009 have been released publicly, along with a video visualization of the surveyed sky.
On 17 March 2010, the first ''Planck'' photos were published, showing dust concentration within 500 light years from the Sun.
On 5 July 2010, the ''Planck'' mission delivered its first all-sky image.
The first public scientific result of ''Planck'' is the Early-Release Compact-Source Catalogue, released during the January 2011 ''Planck conference'' in Paris.
On 5 May 2014 a map of the galaxy's magnetic field created using ''Planck'' was published.
The Planck team and
principal investigator
In many countries, the term principal investigator (PI) refers to the holder of an independent grant and the lead researcher for the grant project, usually in the sciences, such as a laboratory study or a clinical trial. The phrase is also often us ...
s Nazzareno Mandolesi and Jean-Loup Puget shared the 2018
Gruber Prize in Cosmology
The Gruber Prize in Cosmology, established in 2000, is one of three prestigious international awards worth US$500,000 made by the Gruber Foundation, a non-profit organization based at Yale University in New Haven, Connecticut.
Since 2001, the G ...
.
Puget was also awarded the 2018
Shaw Prize in Astronomy.
2013 data release
On 21 March 2013, the European-led research team behind the ''Planck'' cosmology probe released the mission's all-sky map of the cosmic microwave background.
This map suggests the Universe is slightly older than thought: according to the map, subtle fluctuations in temperature were imprinted on the deep sky when the Universe was about 370,000 years old. The imprint reflects ripples that arose as early in the existence of the Universe as the first nonillionth (10
−30) of a second. It is theorised that these ripples gave rise to the present vast
cosmic web
The observable universe is a Ball (mathematics), ball-shaped region of the universe comprising all matter that can be observation, observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electroma ...
of
galactic clusters and
dark matter
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not a ...
. According to the team, the Universe is billion-years-old, and contains ordinary matter, dark matter and
dark energy
In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the univ ...
.
[See Table 9 in ] The
Hubble constant
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving ...
was also measured to be .
2015 data release
Results from an analysis of ''Planck'' full mission were made public on 1 December 2014 at a conference in
Ferrara, Italy.
A full set of papers detailing the mission results were released in February 2015.
Some of the results include:
* More agreement with previous WMAP results on parameters such as the density and distribution of matter in the Universe, as well as more accurate results with less margin of error.
* Confirmation of the Universe having a 26% content of dark matter. These results also raise related questions about the
positron excess over
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
s detected by the
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer (AMS-02) is a particle physics experiment module that is mounted on the International Space Station (ISS).Kristine Rainey (April 2, 2013)Alpha Magnetic Spectrometer (AMS): How It Works NASA. Retrieved June 2, 20 ...
, an experiment on the
International Space Station
The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ( ...
. Previous research suggested that positrons could be created by the collision of dark matter particles, which could only occur if the probability of dark matter collisions is significantly higher now than in the early Universe. ''Planck'' data suggests that the probability of such collisions must remain constant over time to account for the structure of the Universe, negating the previous theory.
* Validation of the simplest models of
inflation
In economics, inflation is an increase in the general price level of goods and services in an economy. When the general price level rises, each unit of currency buys fewer goods and services; consequently, inflation corresponds to a reduct ...
, thus giving the
Lambda-CDM model
The ΛCDM (Lambda cold dark matter) or Lambda-CDM model is a parameterization of the Big Bang cosmological model in which the universe contains three major components: first, a cosmological constant denoted by Lambda (Greek Λ) associated with ...
stronger support.
* That there are likely only three types of
neutrino
A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
s, with a fourth proposed
sterile neutrino
Sterile neutrinos (or inert neutrinos) are hypothetical particles (neutral leptons – neutrinos) that are believed to interact only via gravity and not via any of the other fundamental interactions of the Standard Model. The term ''sterile neutri ...
unlikely to exist.
Project scientists worked too with
BICEP2 scientists to release joint research in 2015 answering whether a signal detected by BICEP2 was evidence of primordial
gravitational waves, or was simple
background noise
Background noise or ambient noise is any sound other than the sound being monitored (primary sound). Background noise is a form of noise pollution or interference. Background noise is an important concept in setting noise levels.
Background n ...
from dust in the Milky Way galaxy.
Their results suggest the latter.
2018 final data release
See also
*
DustPedia
*
Lambda-CDM model
The ΛCDM (Lambda cold dark matter) or Lambda-CDM model is a parameterization of the Big Bang cosmological model in which the universe contains three major components: first, a cosmological constant denoted by Lambda (Greek Λ) associated with ...
*
List of cosmological computation software
*
Observational cosmology
Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors.
Early observations
The science of physical cosmology as it is ...
*
Physical cosmology
Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of f ...
*
Terahertz radiation
Terahertz radiation – also known as submillimeter radiation, terahertz waves, tremendously high frequency
(THF), T-rays, T-waves, T-light, T-lux or THz – consists of electromagnetic waves within the ITU-designated band of fre ...
References
Further reading
*
External links
* ESA
*
''Planck'' mission website*
''Planck'' science website*
''Planck'' operations website*
''Planck'' science results website* NASA
*
''Planck'' mission website*
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